Electrocardiogram Flashcards
What is an 1st degree AV block?
Lengthened delay between atrial and ventricular depolarization; PR interval > .2 seconds
What are the 2 types of 2nd degree AV block?
Wenckebach and Mobitz
Describe Wenckebach
Each P wave and its associated QRS get progressively farther apart in successive cycles until the last doesn’t make it through.
Describe Mobitz
Series of cycles consisting of one normal cycle preceeded by a series of paced P-waves that don’t conduct; A block of the purkinje fibers
P-waves are never premature
What are the EKG findings of Mobitz?
Widened QRS with normal PR interval
Describe a 3rd degree AV block
No conduction of atrial stimuli to the ventricles.
Look for AV dissociation and Escape rhythms.
Discuss Bundle Branch Blocks
Widened QRS > .12s; ‘Rabbit ears’ in V1 or V2 = RBBB
‘Rabbit ears’ in V5 or V6 = LBBB
Discuss the EKG findings of an anterior hemiblock
- Left Axis Deviation
- Q1S3; Significant Q waves in Lead 1, Deep S wave in Lead 3
- Occlusion of Anterior Descending Artery
Discuss the EKG findings of a posterior hemiblock
- Right Axis Deviation
2. Q3S1
Discuss the EKG findings of Atrial Enlargement
Diphasic P-wave in V1;
Large initial component = RAE
Large terminal component = LAE
Discuss the EKG of Right Ventricular Hypertrophy
- Large R wave in V1
- S wave is smaller than R wave in V1
- Right axis deviation
- R wave gets progressively smaller in leads V1,2,3,4
Discuss the EKG of Left Ventricular Hypertrophy
- Exaggerated amplitude of QRS in all chest leads.
- Large S in V1
- Large R in V5
- Inverted T wave with gradual down slope and sharp return
Discuss the EKG findings of Ischemia
Symmetrical inverted T wave; Especially in V2-V6
Discuss the EKG findings of Injury
ST segment elevation; Indicates Acute infarction
Discuss the EKG findings of Pericarditis
Elevated and flat/concave ST segment
What does ST segment depression indicate?
- Subendocardial Infarction: An infarct that doesn’t extend through entire heart wall.
- Digitalis
Discuss the EKG findings of Necrosis
Significant Q waves; At least 1 small box wide OR 1/3 entire QRS amplitude
Discuss the EKG findings of an Anterior wall infarction
- Significant Q waves in V1-V4
If isolated in V1-V2= antero-septal infarction
If isolated in V3-V4= antero-lateral infarction - Occlusion of Anterior Descending branch of the LCA
Discuss the EKG finding of a Lateral Infarction
- Q waves in Leads 1 and AVL
2. Occlusion of Circumflex branch of LCA
Discuss the EKG findings of an inferior wall infarction
- Q waves in Leads 2,3 and AVF
Discuss the EKG findings of a posterior wall infarction
- Large R waves in V1-V3.
- ST depression in V1 or V2
- Occlusion of Right Coronary Artery
Why is a posterior wall infarction (Occlusion of RCA) so dangerous?
RCA supplies blood to the SA node, AV node and Bundle of His
Differentiate between Hyperkalemia and Hypokalemia on an EKG
Hyperkalemia: P-wave flattens and widens, QRS widens, T-wave becomes peaked
Hypokalemia: T wave becomes flat or inverted and a U-wave appears.
Differentiate Wandering Pacemaker from Multifocal Atrial Tachycardia
Both have P’ but with Wandering pacemaker the atrial rate is < 100.
Differentiate WPW syndrome from LGL syndrome
WPW: Delta waves = Premature deplorization of a portion of the ventricles
LGL: No PR interval = No AV delay. P-waves are adjacent to their QRS’
